rt2x00: Remove DEVICE_STATE_DISABLED_RADIO_HW

The DEVICE_STATE_DISABLED_RADIO_HW flag is only read but never set,
it is an ancient part of one of the many versions of the rfkill implementations
in rt2x00. It is about time is disappears.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>